Sleepwalking/ sleep issues are indicative of a child who suffers from anxiety. If I had to guess, I think your child has some extreme anxiety issues that are tied up somehow with his home life-- and you are right you are in a continual pattern/ cycle.
To break it, you need to do a few things:
- you mention everything is a challenge/ argument-- stop arguing -- he does what he needs to do when he needs to do it, or he goes to time out-- every time-- and if he won't be quiet, then put the time out place somewhere where he won't bother anyone else, and ignore him until the tantrum is gone-- this is the only thing to do with a tantrum, really. He can only get your attention when he is not behaving this way. No one in your family should pay him attention during a tantrum.
- you need to seek help from his physicial and/or a mental health practioner. This practioner can give you advice on how to help your child deal with all the negative feelings that he has, and how to help you break the cycle-- so that you can work on repairing the relationship you have. It sounds like at a critical time in his growth his father was not around- and he had you to himself. And then his father came back and then he had a new sibling and he lost his special place with you and got mad-- and then sort of stayed mad - the whole vicious cycle thing. It will take some healing time to resolve I think and I think a professional should guide your family in this process.